Tackified pressure sensitive adhesives

ABSTRACT

A pressure sensitive adhesive that includes: 
     (a) the polymerization product of: 
     (i) 25-98 parts by weight of an acrylic acid ester of a monohydric alcohol whose homopolymer has a T g  less than 0° C.; 
     (ii) 2-75 parts by weight of a non-polar ethylenically unsaturated monomer whose homopolymer has a solubility parameter of no greater than 10.50 and a T g  greater than 15° C.; and 
     (iii) 0-5 parts by weight of a polar ethylenically unsaturated monomer whose homopolymer has a solubility parameter of greater than 10.50 and a T g  greater than 15° C.; and 
     (b) at least one tackifier that is miscible in the polymerization product at room temperature.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 08/469,158, filedJun. 6, 1995, now abandoned, which is a continuation of U.S. Ser. No.08/410,936, filed Mar. 27, 1995 now abandoned, which is a continuationof U.S. Ser. No. 08/150,408, filed Nov. 10, 1993, now abandoned. Thisapplication is related to the following applications, all of which areassigned to the same assignee as the present application and are herebyincorporated by reference: Bennett et all, "Pressure SensitiveThermosetting Adhesives," U.S. Ser. No. 08/08/150,417, filed Nov. 10,1993 now abandoned; Bennett et at., Pressure Sensitive Adhesives WithGood Low Energy surface Adhesion," U.S. Ser. No. 08/150,425, filed Nov.10, 1993 now abandoned; and Bennett et al., "Pressure SensitiveAdhesives With Good Oily Surface Adhesion," U.S. Ser. No. 08/150,426,filed Nov. 10, 1993 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to tackified pressure sensitive adhesives.

2. Description of the Background

Acrylate pressure sensitive adhesives are well known in the art. Many ofthese adhesives are copolymers of an alkyl ester of acrylic acid and aminor portion of a polar co-monomer. Due to the presence of the polarco-monomer these adhesives generally do not adhere well to low energyand oily surfaces (e.g., surfaces having a critical surface tension ofwetting of no greater than about 35 dynes/cm). Although adhesion can beimproved through addition of a tackifier, the degree of improvement islimited because most commercially available tackifiers are not misciblein the polar monomer-containing adhesives.

SUMMARY OF THE INVENTION

In general, the invention features a pressure sensitive adhesive thatincludes:

(a) the polymerization product of:

(i) 25-98 parts by weight of an acrylic acid ester of a monohydricalcohol whose homopolymer has a T_(g) less than 0° C.;

(ii) 2-75 parts by weight of a non-polar ethylenically unsaturatedmonomer whose homopolymer has a solubility parameter of no greater than10.50 and a T_(g) greater than 15° C.;

(iii) 0-5 parts by weight of a polar ethylenically unsaturated monomerwhose homopolymer has a solubility parameter of greater than 10.50 and aT_(g) greater than 15° C.; and

(b) at least one tackifier that is miscible in the polymerizationproduct at room temperature.

By "miscible" it is meant that the final pressure sensitive adhesivedoes not exhibit macroscopic phase separation as evidenced by opticalclarity at room temperature.

In one preferred embodiment, the relative amounts of the acrylic acidester, non-polar ethylenically unsaturated monomer, and polarethylenically unsaturated monomer are chosen such that the 90° peeladhesion of the pressure sensitive adhesive to a polypropylene surfaceis at least 2 lbs/0.5 in. after a 72 hour dwell at room temperature asmeasured according to Test Procedure B1, infra.

In another preferred embodiment, the relative amounts of the acrylicacid ester, non-polar ethylenically unsaturated monomer, and polarethylenically unsaturated monomer are chosen such that the 90° peeladhesion of the pressure sensitive adhesive to a surface provided with1.5±0.25 mg/in² of oil is greater than zero after a 10 second dwell atroom temperature as measured according to Test Procedure B2, infra.

The invention provides tackified pressure sensitive adhesives which, byvirtue of incorporating a non-polar ethylenically unsaturated monomerand limiting the polar monomer content to no more than 5 parts, exhibitgood adhesion to both low energy (e.g., plastics such as polyolefinplastics) and oily surfaces. The adhesives exhibit good adhesion to highenergy surfaces such as stainless steel as well. Because the non-polarmonomer reduces the polarity of the adhesive, commercially availabletackifiers (many of which have low polarity themselves) are miscible inthe adhesives and thus may be used. Thus, rather than tailoring thetackifier to make it miscible with the acrylate polymer, the inventiontailors the properties of the acrylate polymer to make it miscible withthe tackifier.

The adhesives are less toxic than, e.g., adhesives containing polarheteroatom acrylates. The adhesives further exhibit good shearproperties both at low and high temperatures, particularly when a small(no more than 5 parts) of a polar co-monomer is included.

The adhesives offer the further advantage of reduced sensitivity tomoisture and reduced tendency to corrode metals such as copper relativeto pressure sensitive adhesives containing higher amounts of polarco-monomers. Furthermore, the adhesives interact to a lesser extent withpolar additives compared to pressure sensitive adhesives containinghigher amounts of polar co-monomers.

Other features and advantages will be apparent from the followingdescription of the preferred embodiments thereof, and from the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The tackified pressure sensitive adhesives of this invention displaygood adhesion to both low energy surfaces such as polypropylene, highenergy surfaces such as stainless steel, and oily surfaces (e.g., oilymetal). Examples of oily surfaces include surfaces provided with mineraloil, emulsion oils, peanut oil, motor oil (e.g., 5W-30), WD40, andFerricote 61 A US (Quaker Chemical Co.) (a common protectant for coldrolled steel).

The 90° peel adhesion to polypropylene or to steel after a 72 hour dwellat room temperature is at least 2 lbs/0.5 in., preferably at least 3lbs/0.5 in., and more preferably at least 4 lbs/0.5 in. measuredaccording to Test Procedure B1, infra. The 90° peel adhesion to asurface provided with 1.5±0.25 mg/in² of oil after a 10 second dwell atroom temperature is greater than zero, preferably at least 2 oz/0.5 in.,and more preferably at least 4 oz./0.5 in. measured according to TestProcedure B2, infra. After a 1 minute dwell, the adhesion preferablybuilds to at least 5 oz/0.5 in. and more preferably to at least 10oz/0.5 in. measured according to Test Procedure B2, infra.

The adhesives also display good cohesive strength properties as measuredby the shear strength. Preferably, the shear strength at both roomtemperature and 70° C. is greater than 50 minutes, more preferablygreater than 1,000 minutes, and even more preferably greater than 10,000minutes measured according to Test Procedures C1 and C2, infra. Theseproperties are achieved by controlling the monomeric composition toachieve the appropriate polarity (as measured by the solubilityparameter of the homopolymers of the individual monomers determinedaccording to the Fedors technique) and rheological properties (the T_(g)as measured by the 1 radian/second tan delta maximum temperature of theadhesive polymer).

The ability to incorporate a tackifier increases the value of the peelstrength beyond what it would be in the absence of the tackifier. Thetackifier also increases "formulation freedom," i.e., the ability toadjust the properties of the adhesives for particular applications byintroducing another variable, namely, the tackifier.

A list of several common monomers and their respective Fedors'solubility parameters is shown in Table 1. Table 1 is subdivided intofour sections: low Tg acrylate monomers, high Tg acrylate monomers, highTg methacrylate monomers, and vinyl monomers.

                  TABLE 1                                                         ______________________________________                                        FEDORS' SOLUBILITY PARAMETERS                                                                  Solubility Parameter                                         Repeat Unit      (cal/cm.sup.3).sup.0.5                                       ______________________________________                                        Octadecyl acrylate (ODA)                                                                       8.99                                                         Lauryl acrylate (LA)                                                                           9.15                                                         Iso-octyl acrylate (IOA)                                                                       9.22                                                         2-ethylhexyl acrylate (2-                                                                      9.22                                                         EHA)                                                                          Butyl acrylate (BA)                                                                            9.77                                                         Propyl acrylate (PA)                                                                           9.95                                                         Ethyl acrylate (EA)                                                                            10.20                                                        3,3,5 trimethylcyclohexyl                                                                      9.35                                                         acrylate (TMCA)                                                               Iso-bornyl acrylate (IBA)                                                                      9.71                                                         Cyclohexyl acrylate (CHA)                                                                      10.16                                                        N-octyl acrylamide (NOA)                                                                       10.33                                                        Tetrahydrofurfuryl acrylate                                                                    10.53                                                        (THFA)                                                                        Methyl acrylate (MA)                                                                           10.56                                                        Glycidyl acrylate (GA)                                                                         11.32                                                        2-Phenoxyethylacrylate (2-                                                                     11.79                                                        PhEA)                                                                         N-vinylcaprolactam (NVC)                                                                       12.10                                                        N,N,-Dimethylacrylamide                                                                        12.32                                                        (DMA)                                                                         N-vinyl-2-pyrrolidone                                                                          13.38                                                        (NVP)                                                                         Acrylic Acid (AA)                                                                              14.04                                                        Methylmethacrylate                                                                             9.93                                                         (MMA)                                                                         Ethylmethacrylate (EMA)                                                                        9.72                                                         Propylmethacrylate (PMA)                                                                       9.57                                                         Vinyl Acetate    10.56                                                        Styrene          11.87                                                        ______________________________________                                    

The rheological character of the adhesive polymer can be partially butusefully described by the T_(g) as measured by the 1 radian/second tandelta maximum temperature. It is preferable for the 1 radian/second tandelta maximum temperature of the polymer to have a value between -45° C.and 15° C., more preferably between -25° C. and 5° C., and even morepreferably between -20° C. and 0° C.

The adhesives according to the invention having the requisite polarityand rheological properties contain 25-98 parts (more preferably 70-97parts) of an acrylic acid ester whose homopolymer has a T_(g) less than0° C. (more preferably less than -20° C.), 2-75 parts (more preferably3-30 parts) of a non-polar ethylenically unsaturated monomer whosehomopolymer has a T_(g) greater than 15° C., 0-5 parts (more preferably0-3 parts) of a polar ethylenically unsaturated monomer whosehomopolymer has a T_(g) greater than 15° C., and one or more tackifiers.

The acrylic acid ester is a monofunctional acrylic ester of a monohydricalcohol having from about 4 to about 18 carbon atoms in the alcoholmoiety whose homopolymer has a T_(g) less than 0° C. Included in thisclass of acrylic acid esters are isooctyl acrylate, 2-ethylhexylacrylate, isononyl acrylate, isodecyl acrylate, decyl acrylate, laurylacrylate, hexyl acrylate, butyl acrylate, and octadecyl acrylate, orcombinations thereof. In the case of octadecyl acrylate, the amount ischosen such that side chain crystallization does not occur at roomtemperature.

The non-polar ethylenically-unsaturated monomer is a monomer whosehomopolymer has a solubility parameter as measured by the Fedors methodof not greater than 10.50 and a T_(g) greater than 15° C. The non-polarnature of this monomer improves the low energy and oily surface adhesionof the adhesive. It also improves the structural properties of theadhesive (e.g., cohesive strength) relative to a homopolymer of theacrylic acid ester described above. Examples of suitable non-polarmonomers include 3,3,5 trimethylcyclohexyl acrylate, cyclohexylacrylate, isobornyl acrylate, N-octyl acrylamide, t-butyl acrylate,methyl methacrylate, ethyl methacrylate, and propyl methacrylate orcombinations thereof.

The adhesive may contain a limited quantity (e.g., no more than 5 parts)of a polar ethylenically unsaturated monomer whose homopolymer has asolubility parameter as measured by the Fedors method of greater than10.50 and a T_(g) greater than 15° C. to improve structural properties(e.g., cohesive strength). It is not desirable to include more than 5parts of the polar monomer because the polar monomer impairs low energyand oily surface adhesion, and reduces tackifier miscibility. Examplesof suitable polar monomers include acrylic acid, itaconic acid, certainsubstituted acrylamides such as N,N dimethylacrylamide,N-vinyl-2-pyrrolidone, N-vinyl caprolactam, acrylonitrile,tetrahydrofurfuryl acrylate, glycidyl acrylate, 2-phenoxyethylacrylate,and benzylacrylate, or combinations thereof.

The tackifier must be miscible with the acrylate-containing polymer ofthe adhesive such that macroscopic phase separation does not occur inorder to improve the properties of the adhesive. Preferably, theadhesive is free of microscopic phase separation as well. Mostcommercially available tackifiers are hydrocarbon-based and thus of lowpolarity. Such tackifiers ordinarily are not miscible with conventional,polar monomer-containing adhesives. However, by incorporating anon-polar monomer into the adhesive (thereby increasing the non-polarcharacter of the adhesive) the invention allows a variety ofcommercially available tackifiers to be used. The total amount oftackifer is preferably 5-60 parts per 100 parts acrylate-containingpolymer, and more preferably about 15-30 parts. The particular amount oftackifier depends on the composition of the acrylate-containing polymerand is generally selected to maximum peel properties withoutcompromising desired shear strength.

Because the adhesives are preferably prepared by polymerizing themonomers in the presence of the tackifier according to a free radicalprocess, it is further desirable to select a tackifier that does notsubstantially impede the polymerization process, e.g., by acting as afree radical scavenger, chain termination agent, or chain transferagent. A measure of the ability of the tackifier to inhibit free radicalpolymerization in a bulk polymerization process for a given processcondition is defined here as the "inhibition factor." The inhibitionfactor (IF) is determined from the monomer conversion test and is theratio of (1) the percent volatiles of the tackified sample (C_(t)) lessthe percent volatiles of an identically formulated and processed samplewithout tackifier (C_(o)) and (2) the percent volatiles of anidentically formulated and processed sample without tackifier (C_(o)).The inhibition factor equation is shown below: ##EQU1##

Although a wide variety of tackifiers may be used, in cases where freeradical polymerization is involved the class of tackifiers known underthe tradename Regalrez resins commercially available from Hercules arepreferred. These tackifiers are produced by polymerization andhydrogenation of pure monomer hydrocarbon feed stock. Suitable resinsinclude Regalrez resins 1085, 1094, 6108, and 3102.

The monomer mixture can be polymerized by various techniques, withphotoinitiated bulk polymerization being preferred. An initiator ispreferably added to aid in polymerization of the monomers. The type ofinitiator used depends on the polymerization process. Photoinitiatorswhich are useful for polymerizing the acrylate monomers include benzoinethers such as benzoin methyl ether or benzoin isopropyl ether,substituted benzoin ethers such as 2-methyl-2-hydroxylpropiophenone,aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, andphotoactive oxides such asphenyl-1,2-propanedion-2-(o-ethoxycarbonyl)oxime. An example of acommercially available photoinitiator is Irgacure™ 651 available fromCiba-Geigy Corporation, having the formula2,2-dimethoxy-1,2-diphenylethane-1-one). Generally, the photoinitiatoris present in an amount of about 0.005 to 1 weight percent based on theweight of the monomers. Examples of suitable thermal initiators includeAIBN and peroxides.

The mixture of the polymerizable monomers may also contain acrosslinking agent, or a combination of crosslinking agents, to increasethe shear strength of the adhesive. Useful crosslinking agents includesubstituted triazines such as 2,4,-bis(trichloromethyl)-6-(4-methoxyphenyl)-s-triazine,2,4-bis(trichloromethyl)-6-(3,4-dimethoxyphenyl)-s-triazine, and thechromophore-substituted halo-s-triazines disclosed in U.S. Pat. Nos.4,329,384 and 4,330,590 (Vesley) incorporated herein by reference. Otheruseful crosslinking agents include multifunctional alkyl acrylatemonomers such as trimetholpropane triacrylate, pentaerythritoltetra-acrylate, 1,2 ethylene glycol diacrylate, 1,4 butanedioldiacrylate, 1,6 hexanediol diacrylate, and 1,12 dodecanol diacrylate.Various other crosslinking agents with different molecular weightsbetween (meth)acrylate functionality would also be useful. Generally,the crosslinker is present in an amount of abut 0.005 to 1 weightpercent based on the weight of the monomers.

Where a foam-like pressure sensitive adhesive tape is desired, a monomerblend containing microspheres may be used. Suitable microspheres arecommercially available from from Kema Nord Plastics under the trade name"Expancel" and from Matsumoto Yushi Seiyaku under the trade name"Micropearl". When expanded the microspheres have a specific density ofapproximately 0.02-0.036 g/cc. It is possible to include the unexpandedmicrospheres in the pressure sensitive adhesive composition andsubsequently heat them to cause expansion when they are appropriatelyprocessed, but it is generally preferred to mix the expandedmicrospheres into the adhesive. This process makes it easier to ensurethat the hollow microspheres in the final adhesive are substantiallysurrounded by at least a thin layer of adhesive.

Polymeric microspheres having a average diameter of 10 to 200micrometers may be blended into the polymerizable composition in amountsfrom about 15% to about 75% by volume prior to coating. Also useful areglass microspheres having an average diameter of from 5 to 200micrometers, preferably from about 20 to 80 micrometers. Suchmicrospheres may comprise 5% to 65% by volume of the pressure sensitiveadhesive. Both polymeric and glass microspheres are known in the art.The pressure sensitive adhesive layer of the tape should be at least 3times as thick as the diameter of the microspheres, preferably at least7 times.

Other tape constructions in which the pressure sensitive adhesivesaccording to the invention are useful include mechanical fasteners suchas Dual-Lock™ brand fastener (Minnesota Mining and Manufacturing Co.,St. Paul, Minn.) and Scotchmate™ brand fastener (Minnesota Mining andManufacturing Co., St. Paul, Minn.). The pressure sensitive adhesivesare also useful in vibration damping applications.

Other materials which can be blended with the polymerizable monomersprior to coating include plasticizers, coloring agents, reinforcingagents, fire retardants, foaming agents, thermally conductive agents,electrically conductive agents, post-curing agents, and post-curingagent curatives and their accelerators, and the like.

The pressure sensitive adhesives according to the invention arepreferably prepared by photoinitiated bulk polymerization according tothe technique described in Martens et al., U.S. Pat. No. 4,181,752,hereby incorporated by reference. The polymerizable monomers and aphotoinitiator are mixed together in the absence of solvent andpartially polymerized to a viscosity in the range of from about 500 cpsto about 50,000 cps to achieve a coatable syrup. Alternatively, themonomers may be mixed with a thixotropic agent such as fumed hydrophilicsilica to achieve a coatable thickness. The crosslinking agent and anyother ingredients (including the tackifier) are then added to theprepolymerized syrup. Alternatively, with the exception of thecrosslinking agent, these ingredients (including the tackifier) may beadded directly to monomers.

The resulting composition is coated onto a substrate (which may betransparent to ultraviolet radiation) and polymerized in an inert (i.e.,oxygen free) atmosphere, e.g., a nitrogen atmosphere by exposure toultraviolet radiation. Examples of suitable substrates include releaseliners (e.g., silicone release liners) and tape backings (which may beprimed or unprimed paper or plastic). A sufficiently inert atmospherecan also be achieved by covering a layer of the polymerizable coatingwith a plastic film which is substantially transparent to ultravioletradiation, and irradiating through that film in air as described in theaforementioned Martens et al. patent using ultraviolet lamps.Alternatively, instead of covering the polymerizable coating, anoxidizable tin compound may be added to the polymerizable syrup toincrease the tolerance of the syrup to oxygen as described in U.S. Pat.No. 4,303,485 (Levens). The ultraviolet light source preferably has 90%of the emissions between 280 and 400 nm (more preferably between 300 and400 nm), with a maximum at 351 mm.

The tackifier may also be added after polymerization of the acrylatemonomers.

Where multi-layer tape constructions are desirable, one method ofconstruction is multi-layer coating using conventional techniques. Forexample, the coating may be applied concurrently (e.g., through a diecoater), after which the entire multi-layer structure is cured all atonce. The coatings may also be applied sequentially whereby eachindividual layer is partially or completely cured prior to applicationof the next layer.

The invention will now be further described by way of the followingexamples.

EXAMPLES

Test Procedures

Test procedures used in the examples to evaluate pressure sensitiveadhesives include the following.

Monomer Conversion Test (Test Procedure A1)

The monomer conversion was determined gravimetrically. A sample of theadhesive was weighed after it was coated and subsequently dried at 120°C. for 3 hours and then re-weighed. The percent volatiles was taken tobe indicative of the monomer conversion.

Monomer Conversion Test (Test procedure A2)

The monomer conversion was determined gravimetrically. 3 in. by 3 in.samples were laminated to a piece of aluminum foil, weighed, and placedin a forced air oven at 250° F. for 90 min. Samples were thenequilibrated at room temperature and re-weighed for weight loss. Thepercent volatiles was taken to be indicative of the monomer conversion.

90° Peel Adhesion Test (Test Procedure B1)

One-half inch wide strips of a 5 mil adhesive sample were carefully cutand placed onto the substrate of interest. A 5 mil anodized aluminumbacking, 0.625 in, wide, was then laminated to the adhesive which isapproximately 5 inches long. Test substrates of interest included lowenergy surfaces such as polypropylene (2"×5"×3/16" natural polypropylenepanels available from Precision Punch and Plastic, Minneapolis, Minn.,having a mask on both sides that is removed prior to cleaning andtesting) and polycarbonate (Lexan™ available from General Electric Co.),and high energy surfaces such as stainless steel (304-2BA 28 gaugestainless steel with a surface roughness of 2.0±1.0 microinches). A freeend of the backing to which the adhesive was laminated extended beyondthe test substrate so that it could be clamped to a load cell todetermine peel strength. The sample was rolled twice back and forth witha 2 kg hard rubber roller to ensure contact between the adhesive and thetest substrate. The adhesive was then removed after a given dwell time(usually 72 hours unless otherwise noted) at 12"/minute in a 90° peelmode. The peel data are reported in lbs/0.5 in. width. and represent theaverage of two tests.

The stainless steel substrates were washed once with acetone and 3 timeswith a 50/50 isopropanol/water mixture prior to testing. The plasticsubstrates were washed 3 times with heptane prior to testing.

90° Peel Adhesion Test (Test procedure B2)

One-half inch wide pieces of samples were cut out and laminated to 5 milthick anodized aluminum which was 0.625 in. wide. The adhesive thicknesswas 5 mils. The release liner was then removed from the adhesive and thesamples were placed onto either a stainless steel substrate (304stainless steel with a #7 finish) or a cold rolled steel substrate (20gauge cold plate CRS 1018 with mill finish). The stainless steelsubstrate was cleaned prior to application of adhesive by wiping oncewith acetone and 3 times with heptane. The cold rolled steel substratewas cleaned prior to application of adhesive by wiping once withacetone.

Prior to application of the adhesive, an excess of mineral oil wasapplied to each cold rolled steel substrate with a small piece of cheesecloth and then removed to leave a coating of oil that was 1.5±0.25mg/in.². A free end of the backing to which the adhesive was laminatedextended beyond the test substrate so that it could be clamped to a loadcell to determine peel strength. The sample was rolled back and forthtwice with a 4.5 lb roller to ensure contact between the adhesive andthe test substrate. The adhesive was then removed after a given dwelltime (10 sec., 1 minute, or 24 hours) at 12"/minute in a 90° peel mode.

The values reported are in oz/0.5 in. and represent the average peelvalues (based on two tests) obtained between 1 and 4 inches on a 5 inchpeel sample. All tests were done at room temperature.

Shear Test (Test procedure C1)

A 0.5 inch strip of tape was adhered to a piece of stainless steel (304stainless steel with a #7 finish) which had been cleaned once withacetone and 3 times with 50/50 isopropanol/water such that a one-halfsquare inch overlap was accomplished. A piece of 5 mil anodized aluminumwas then laminated to the entire area of the pressure sensitiveadhesive, leaving an additional area to which a load could be applied.The thickness of the adhesive was 5 mils. The sample was then rolledtwice back and forth with a 15 pound roller and allowed to dwell forfour hours. The 70° C. samples were further allowed to dwell for 10minutes at 70° C. After dwelling the sample was tested at either roomtemperature or 70° C. At room temperature a 1 kg load was applied to theadhesive and the time before the load fell was recorded. At 70° C. a 500g load was applied to the adhesive and the time before the load fell wasrecorded.

The shear data are reported in minutes and represent the average of twotests.

Shear Test (Test Procedure C2)

One-half inch wide pieces of samples were cut out and laminated to 5 milthick anodized aluminum which was 0.625 in. wide. This construction wasplaced on stainless steel panels (304 stainless steel with a #7 finish)that had been cleaned by wiping once with acetone and 3 times withheptane. Placement was such that a 1.0 in.×0.5 in. adhesive sample(adhesive thickness=5 mils) was in contact with the panel. The adhesivesample was rolled back and forth twice with a 4.5 lb roller, with someexcess material overhanging the sample for attachment of the weight. Thesamples were then allowed to dwell for 24 hours before the weight washung on the samples. The 70° C. samples were further allowed to dwellfor an additional 10 minutes in the oven before the weight was applied.For the room temperature samples, a 1000 g weight was used, whereas forthe 70° C. samples a 500 g weight was used.

The shear data are reported in minutes until the weight fell andrepresent the average of two tests.

Phase Separation (Test Procedure D)

The presence or absence of phase separation was judged by the opticalclarity of the resulting polyacrylate/tackifier blend. The visualobservation of opacity was taken to be indicative of a phase separation.

EXAMPLES Examples 1-56

Example 1

100 parts by weight of iso-octyl acrylate (IOA), iso-bornyl acrylate(IBA), and acrylic acid (AA) with a monomer ratio of 80/19.5/0.5(IOA/IBA/AA) was blended with 0.04 parts of benzildimethylketal (KB-1,SARTOMER Company) photoinitiator and photopolymerized with anultraviolet light source under a constant nitrogen purge to a viscosityof about 2000 cps. 0.16 parts of additional benzildimethylketalphotoinitiator, 0.15 parts of2,4-bis(trichloromethyl)-6-(4-methoxyphenyl), and 20 parts of Regalrez1085 tackifier resin (Hercules Co.) were added to the acrylate syrup andmixed until all of the components had completely dissolved. Aftermixing, the blend was knife-coated at a 5 mil thickness onto asilicone-treated polyethylene-coated paper release liner. The compositewas then exposed to ultraviolet radiation having a spectral output from300-400 with a maximum at 351 nm in a nitrogen-rich environment. Theaverage intensity was about 2.05 mW/cm². resulting in a total energy of650 mJ/cm².

Example 2 was prepared in the same way as Example 1 except 40 parts ofRegalrez 1085 tackifier was used.

Example 3 was prepared in the same way as Example 1 except Regalrez 1094tackifier (Hercules Co.) was used.

Example 4 was prepared in the same way as Example 1 except 40 parts ofRegalrez 1094 tackifier was used.

Example 5 was prepared in the same way as Example 1 except Regalrez 1128tackifier (Hercules Co.) was used.

Example 6 was prepared in the same way as Example 1 except 40 parts ofRegalrez 1128 tackifier was used.

Example 7 was prepared in the same way as Example 1 except Regalrez 6108tackifier (Hercules Co.) was used.

Example 8 was prepared in the same way as Example 1 except 40 parts ofRegalrez 6108 tackifier was used.

Example 9 was prepared in the same way as Example 1 except Regalrez 3102tackifier (Hercules Co.) was used.

Example 10 was prepared in the same way as Example 1 except 40 parts ofRegalrez 3102 tackifier was used.

Example 11 was prepared in the same way as Example 1 except Regalrez5095 tackifier (Hercules Co.) was used.

Example 12 was prepared in the same way as Example 1 except 40 parts ofRegalrez 5095 tackifier was used.

Example 13 was prepared in the same way as Example 1 except Escorez 5340tackifier (Exxon Co.) was used.

Example 14 was prepare in the same way as Example 1 except 40 parts ofEscorez 5340 tackifier was used.

Example 15 was prepared in the same way as Example 1 except ArakawaKE-311 tackifier (Arakawa) was used.

Example 16 was prepared in the same way as Example 1 except 40 parts ofArakawa KE-311 tackifier was used.

Example 17 was prepared in the same way as Example 1 except Escorez 5300tackifier (Exxon Co.) was used.

Example 18 was prepared in the same way as Example 1 except 40 parts ofEscorez 5300 tackifier was used.

Example 19 was prepared in the same way as Example 1 except Arkon E90tackifier (Arakawa) was used.

Example 20 was prepared in the same way as Example 1 except 40 parts ofArkon E90 tackifier was used.

Example 21 was prepared in the same way as Example 1 except Arkon P115tackifier (Arakawa) was used.

Example 22 was prepared in the same way as Example 1 except 40 parts ofArkon P115 tackifier was used.

Example 23 was prepared in the same way as Example 1 except Regalite 90tackifier (Hercules Co.) was used.

Example 24 was prepared in the same way as Example 1 except 40 parts ofRegalite 90 tackifier was used.

Example 25 was prepared in the same way as Example 1 except Exxon ECR165B tackifier was used.

Example 26 was prepared in the same way as Example 1 except 40 parts ofExxon ECR 165B tackifier was used.

Example 27 was prepared in the same way as Example 1 except Exxon ECR177 tackifier was used.

Example 28 was prepared in the same way as Example 1 except 40 parts ofExxon ECR 177 tackifier was used.

Example 29 was prepared in the same way as Example 1 except Arkon M100tackifier (Arakawa) was used.

Example 30 was prepared in the same way as Example 1 except 40 parts ofArkon M100 tackifier was used.

Example 31 was prepared in the same way as Example 1 except Arkon M90tackifier (Arakawa) was used.

Example 32 was prepared in the same way as Example 1 except 40 parts ofArkon M90 tackifier was used.

Example 33 was prepared in the same way as example 1 except HercotacRT110 tackifier (Hercules Co.) was used.

Example 34 was prepared in the same way as Example 1 except 40 parts ofHercotac RT110 tackifier was used.

Example 35 was prepared in the same way as example 1 except Escorez 5380tackifier (Exxon Co.) was used.

Example 36 was prepared in the same way as Example 1 except 40 parts ofEscorez 5380 tackifier was used.

Example 37 was prepared in the same way as Example 1 except Foral 85tackifier (Hercules Co.) was used.

Example 38 was prepared in the same way as Example 1 except 40 parts ofForal 85 tackifier was used.

Example 39 was prepared in the same way as Example 1 except Kristalex5140 tackifier (Hercules Co.) was used.

Example 40 was prepared in the same way as Example 2 except 40 parts ofKristalex 5140 tackifier was used.

Example 41 was prepared in the same way as Example 1 except Hercotac100S tackifier (Hercules Co.) was used.

Example 42 was prepared in the same way as Example 1 except 40 parts ofHercotac 100S tackifier was used.

Example 43 was prepared in the same way as Example 1 except Regalite 355tackifier (Hercules Co.) was used.

Example 44 was prepared in the same way as Example 1 except 40 parts ofRegalite 355 tackifier was used.

Example 45 was prepared in the same way as Example 1 except WingtackPlus tackifier (Goodyear Co.) was used.

Example 46 was prepare in the same way as Example 1 except 40 parts ofWingtack Plus tackifier was used.

Example 47 was prepared in the same way as Example 1 except Hercotac RT400 tackifier (Hercules Co.) was used.

Example 48 was prepared in the same way as Example 1 except 40 parts ofHercotac RT 400 tackifier was used.

Example 49 was prepared in the same way as Example 1 except PiccotacHM2162 tackifier (Hercules Co.) was used.

Example 50 was prepared in the same way as Example 1 except 40 parts ofPiccotac HM2162 tackifier was used.

Example 51 was prepared in the same way as Example 1 except Kristalex3100 tackifier (Hercules Co.) was used.

Example 52 was prepared in the same way as Example 1 except 40 parts ofKristalex 3100 tackifier was used.

Example 53 was prepared in the same way as Example 1 except Kristalex1120 tackifier (Hercules Co.) was used.

Example 54 was prepared in the same way as Example 1 except 40 parts ofKristalex 1120 tackifier was used.

Example 55 was prepared in the same way as Example 1 except PiccolyteA135 tackifier (Hercules Co.) was used.

Example 56 was prepared in the same way as Example 1 except 40 parts ofPiccolyte A135 tackifier was used.

The inhibition factor and phase separation characteristics of the aboveexamples are shown in Table 2. The polypropylene peel strength ofseveral samples were determined according to Test Procedure B1 and arereported in Table 2 as well. If the samples possessed an inhibitionfactor greater than 1.0 the sample was dried in a 120° C. oven to reducethe inhibition factor below 1 prior to testing. The designation "nt"means not tested. The designation "na" means not applicable. Thedesignation "nc" means not conclusive.

                  TABLE 2                                                         ______________________________________                                                                      Polypropylene                                            Inhibition  Phase    peel strength                                   Example  Factor      separation                                                                             (lb/0.5")                                       ______________________________________                                        1        0.06        no       nt                                              2        0.11        no       nt                                              3        0.14        no       nt                                              4        0.37        yes      3.37                                            5        0.16        yes      3.20                                            6        0.54        yes      2.71                                            7        0.19        no       2.48                                            8        0.40        no       1.52                                            9        0.20        no       2.78                                            10       0.39        no       1.07                                            11       0.34        no       nt                                              12       0.80        no       nt                                              13       0.46        yes      nt                                              14       1.06        yes      nt                                              15       0.51        no       2.53                                            16       1.42        no       3.90                                            17       0.73        yes      nt                                              18       1.30        yes      nt                                              19       0.74        no       4.29                                            20       1.25        no       1.90                                            21       0.76        yes      3.01                                            22       1.31        no       3.60                                            23       0.78        no       nt                                              24       1.33        no       nt                                              25       0.80        yes      nt                                              26       1.33        Yes      nt                                              27       0.81        yes      nt                                              28       1.22        yes      nt                                              29       0.89        no       2.93                                            30       1.89        no       3.90                                            31       0.96        no       2.72                                            32       1.88        no       4.04                                            33       1.25        no       1.26                                            34       3.11        yes      0.79                                            35       1.34        yes      nt                                              36       2.42        yes      nt                                              37       1.52        no       nt                                              38       2.83        no       nt                                              39       1.61        nc       nt                                              40       2.71        nc       0.69                                            41       1.66        no       2.29                                            42       4.58        no       2.10                                            43       2.25        no       5.14                                            44       2.99        no       2.94                                            45       2.34        no       3.06                                            46       5.74        no       5.33                                            47       2.68        no       2.90                                            48       5.95        no       0.72                                            49       2.94        no       2.82                                            50       6.50        no       3.98                                            51       3.03        nc       nt                                              52       4.11        nc       0.55                                            53       >6.5        na       nt                                              54       >6.5        na       nt                                              55       >6.5        na       nt                                              56       >6.5        na       nt                                              ______________________________________                                    

The data of Table 2 shows that several commercial tackifiers are solublein the non-polar acrylate pressure sensitive adhesive matrix but thatonly the Regalrez tackifying resins have low inhibition factors as well.

EXAMPLES 57-115

Example 57 was prepared in the same way as Example 1 except an 85/15/0IOA/IBA/AA monomer ratio was used.

Example 58 was prepared in the same way as Example except 40 parts ofRegalrez 1085 tackifier was used.

Example 59 was prepared in the same way as Example 1 except an 85/14/1IOA/IBA/AA monomer ratio was used.

Example 60 was prepared in the same way as Example 1 except an 85/13/2IOA/IBA/AA monomer ratio was used.

Example 61 was prepared in the same way as Example 1 except an 85/11/4IOA/IBA/AA monomer ratio was used.

Example 62 was prepared in the same way as Example 57 except 20 parts ofRegalrez 6108 tackifier was used.

Example 63 was prepared in the same way as Example 62 except 40 parts ofRegalrez 6108 tackifier was used.

Example 64 was prepared in the same way as Example 62 except anIOA/IBA/AA ratio of 85/14/1 was used.

Example 65 was prepared in the same way as Example 64 except 40 parts ofRegalrez 6108 tackifier was used.

Example 66 was prepared in the same way as Example 64 except anIOA/IBA/AA ratio of 85/13/2 was used.

Example 67 was prepared in the same way as Example 66 except anIOA/IBA/AA ratio of 85/12/3 was used.

Example 68 was prepared in the same way as Example 57 except 20 parts ofRegalrez 3102 tackifier was used.

Example 69 was prepared in the same way as Example 68 except 40 parts ofRegalrez 3102 tackifier was used.

Example 70 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 85/14/1 was used.

Example 71 was prepared in the same way as Example 70 except 40 parts ofRegalrez 3102 tackifier was used.

Example 72 was prepared in the same way as Example 70 except anIOA/IBA/AA ratio of 85/13/2 was used.

Example 73 was prepared in the same way as Example 72 except anIOA/IBA/AA ratio of 85/12/3 was used.

Example 74 was prepared in the same way as Example 57 except 20 parts ofRegalrez 1094 tackifier was used.

Example 75 was prepared in the same way as Example 74 except 40 parts ofRegalrez 1094 tackifier was used.

Example 76 was prepared in the same way as Example 74 except anIOA/IBA/AA ratio of 85/14/1 was used.

Example 77 was prepared in the same way as Example 74 except anIOA/IBA/AA ratio of 85/13/2 was used.

Example 78 was prepared in the same way as Example 57 except anIOA/IBA/AA ratio of 90/9/1 was used.

Example 79 was prepared in the same way as Example 78 except anIOA/IBA/AA ratio of 81/13/1 was used.

Example 80 was prepared in the same way as Example 79 except 30 parts ofRegalrez 1085 was used.

Example 81 was prepared in the same way as Example 79 except anIOA/IBA/AA ratio of 76/23/1 was used.

Example 82 was prepared in the same way as Example 81 except 40 parts ofRegalrez 1085 was used.

Example 83 was prepared in the same way as Example 81 except anIOA/IBA/AA ratio of 81/17/2 was used.

Example 84 was prepared in the same way as Example 81 except anIOA/IBA/AA ratio of 76/22/2 was used.

Example 85 was prepared in the same way as Example 62 except anIOA/IBA/AA ratio of 90/9/1 was used.

Example 86 was prepared in the same way as Example 85 except 30 parts ofRegalrez 6108 was used.

Example 87 was prepared in the same way as Example 85 except anIOA/IBA/AA ratio of 81/18/1 was used.

Example 88 was prepared in the same way as Example 87 except 40 parts ofRegalrez 5108 was used.

Example 89 was prepared in the same way as Example 85 except anIOA/IBA/AA ratio of 76/23/1 was used.

Example 90 was prepared in the same way as Example 89 except 40 parts ofRegalrez 5108 was used.

Example 91 was prepared in the same way as Example 85 except anIOA/IBA/AA ratio of 90/8/2 was used.

Example 92 was prepared in the same way as Example 91 except anIOA/IBA/AA ratio of 85/13/2 was used.

Example 93 was prepared in the same way as Example 92 except anIOA/IBA/AA ratio of 81/17/2 was used.

Example 94 was prepared in the same way as Example 93 except 30 parts ofRegalrez 6108 was used.

Example 95 was prepared in the same way as Example 94 except 40 parts ofRegalrez 6108 was used.

Example 96 was prepared in the same way as Example 92 except anIOA/IBA/AA ratio of 76/22/2 was used.

Example 97 was prepared in the same way as Example 96 except 30 parts ofRegalrez 6108 was used.

Example 98 was prepared in the same way as Example 97 except 40 parts ofRegalrez 6108 was used.

Example 99 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 90/9/1 was used.

Example 100 was prepared in the same way as Example 99 except 30 partsof Regalrez 3102 was used.

Example 101 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 81/18/1 was used.

Example 102 was prepared in the same way as Example 101 except 30 partsof Regalrez 3102 was used.

Example 103 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 76/23/1 was used.

Example 104 was prepared in the same way as Example 103 except 30 partsof Regalrez 3102 was used.

Example 105 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 90/8/2 was used.

Example 106 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 81/17/2 was used.

Example 107 was prepared in the same way as Example 106 except 40 partsof Regalrez 3102 was used.

Example 108 was prepared in the same way as Example 68 except anIOA/IBA/AA ratio of 76/22/2 was used.

Example 109 was prepared in the same was as Example 74 except 10 partsof Regalrez 1094 was used and a monomer ratio of 90/9/1 IOA/IBA/AA wasused.

Example 110 was prepared in the same way as Example 74 except a monomerratio of 81/18/1 IOA/IBA/AA was used.

Example 111 was prepared in the same way as Example 109 except a monomerratio of 76/23/1 IOA/IBA/AA was used.

Example 112 was prepared in the same way as Example 111 except 20 partsof Regalrez 1094 was used.

Example 113 was prepared in the same way as Example 109 except 10 partsof Regalrez 3102 was used, 0.09 parts of2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-s-triazine crosslinker wasused, N-octyl acrylamide (NOA) was used instead of IBA, and the monomerratio was 89/10.5/0.5 IOA/NOA/AA.

Example 114 was prepared in the same way as Example 113 except that 30parts Regalrez 3102 was used.

Example 115 was prepared in the same way as Example 62 except anIOA/IBA/AA ratio of 95/4.75/0.25 was used and 25 parts Regalrez 6108 wasused.

COMPARATIVE EXAMPLES C1

90 parts by weight of iso-octyl acrylate (IOA) and 10 parts acrylic acid(AA) were blended with 0.04 parts of 2,2-dimethoxy-2-phenylacetophenonephotoinitiator (Irgacure™ 651, available from Ciba-Geigy Corp.) andphotopolymerized with an ultraviolet light source under a constantnitrogen purge to a viscosity of about 3000 cps. 0.16 parts ofadditional 2,2-dimethoxy-2-phenylacetophenone photoinitiator and 0.15parts of 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-s-triazine wereadded to the acrylate syrup and mixed until all of the components hadcompletely dissolved. After mixing the blend was knife-coated at a 5 milthickness onto a silicone-treated polyethylene-coated paper releaseliner. The composite was then exposed to ultraviolet radiation having aspectral output from 300-400 with a maximum at 351 nm in a nitrogen-richenvironment. An intensity of about 1.0 mW/cm² was used for the firstone-third of the exposure time and an intensity of about 2.2 mW/cm² wasused for the second two-thirds of the exposure time, resulting in atotal energy of 250 mJ/cm².

Comparative example C2 was prepared in the same way as comparativeexample C1 except a premix of 94 parts IOA and 6 parts AA was used.

Comparative example C3 was prepared in the same way as comparativeexample C1 except a premix of 100 parts IOA and 6 parts AA was used.

The data of Example 57-115 and comparative examples C1, C2, and C3 areshown in Table 3. Test procedures A1, B1, and C1 were used to generatethe data. The designation "nt" means not tested.

                                      TABLE 3                                     __________________________________________________________________________                Polypropylene                                                          St. St. Peel                                                                         peel   Room Temp   Percent                                        Example                                                                            (lb/0.5")                                                                            (lb/0.5")                                                                            Shear 70° C. Shear                                                                 Conversion                                     __________________________________________________________________________    57   3.83   3.63    313  35    >98.5%                                         58   3.73   3.87   1006  6     >98.5%                                         59   4.15   4.05   5867  10K+  >98.5%                                         60   2.66   2.84   7222  10K+  >98.5%                                         61   2.71   2.75   10K+  859   >98.5%                                         62   3.15   3.64    535  34    >98.5%                                         63   4.03   6.24    719  23    >98.5%                                         64   4.22   3.54   7223  10K+  >98.5%                                         65   5.33   6.84   2916  41    >98.5%                                         66   6.92   3.85   10K+  10K+  >98.5%                                         67   4.04   3.30   10K+  10K+  >98.5%                                         68   3.21   2.52    880  30    >98.5%                                         69   4.24   2.57    632  5     >98.5%                                         70   4.11   2.67   4900  10K+  >98.5%                                         71   4.94   3.04   1338  12    >98.5%                                         72   3.62   2.58   10K+  10K+  >98.5%                                         73   4.27   3.63   10K+  10K+  >98.5%                                         74   2.58   3.24    708  nt    >98.5%                                         75   3.22   3.26   1301  nt    >98.5%                                         76   3.50   3.54   10K+  10K+  >98.5%                                         77   3.90   3.38   10K+  10K+  >98.5%                                         78   2.69   3.55   2003  1870  >98.5%                                         79   3.24   3.57   10K+  3961  >98.5%                                         80   2.57   2.47   1865  27    >98.5%                                         81   4.32   3.34   4639  1714  >98.5%                                         82   3.00   3.91    242  5     >98.5%                                         83   3.05   3.00   5021  1902  >98.54                                         84   3.39   3.56   3040  888   >98.5%                                         85   3.28   2.82   10K+  10K+  >98.5%                                         86   3.36   4.87   10K+  5307  >98.54                                         87   4.96   3.01   10K+  10K+  >98.5%                                         88   5.60   5.65   2094  22    >98.5%                                         89   3.76   3.43   10K+  1376  >98.5%                                         90   4.76   3.10   5605  18    >98.5%                                         91   3.34   2.87   10K+  10K+  >98.5%                                         92   6.92   3.85   10K+  10K+  >98.5%                                         93   4.86   3.35   10K+  10K+  >98.5%                                         94   4.20   4.61   10K+  1287  >98.5%                                         95   5.73   3.18   10K+  60    >98.5%                                         96   4.55   1.75   10K+  10K+  >98.5%                                         97   5.88   5.44   10K+  207   >98.5%                                         98   4.58   4.38   7187  26    >98.5%                                         99   3.08   2.29   10K+  10K+  >98.5%                                         100  4.55   2.43   4516  1795  >98.5%                                         101  4.64   3.22   5396  10K+  >98.5%                                         102  4.68   1.63   2513  13    >98.5%                                         103  3.81   3.00   6798  10K+  >98.5%                                         104  4.89   1.64   10K+  155   >98.5%                                         105  3.72   2.41   10K+  10K+  >98.5%                                         106  3.61   1.96   10K+  10K+  >98.5%                                         107  6.63   4.62   4906  49    >98.5%                                         108  4.46   4.11   10K+  10K+  >98.5%                                         109  2.38   2.85   223   10K+  >98.5%                                         110  3.06   3.90   10K+  10K+  >98.5%                                         111  2.68   3.05   10K+  10K+  >98.5%                                         112  4.58   4.54   10K+  10K+  >98.5%                                         113  2.65   2.46   2297  150   >98.5%                                         114  3.66   4.06    616  12    >98.5%                                         115  nt     nt     2504  329   >98.5%                                         C1   5.33   0.43   10,000+                                                                             10,000+                                                                             >98.5%                                         C2   3.73   1.29   10,000+                                                                             10,000+                                                                             >98.5%                                         C3   1.35   1.53     2   3     >98.5%                                         __________________________________________________________________________

EXAMPLES 116-124 Example 116

83 parts IOA and 17 parts IBA were mixed together in a jar under aconstant nitrogen purge along with 0.04 parts of Irgacure 651photoinitiator from Ciba-Geigy Corp.(2,2-dimethoxy-2-phenylacetophenone). This mixture was exposed to a lowintensity ultraviolet light under a constant nitrogen purge whilestirring until a coatable viscosity syrup was obtained. The conversionof this syrup was between 4 and 10% and the viscosity was about 3,000cps. 0.12 parts of2,4-bis(trichloromethyl)-6-(3,4-dimethoxyphenyl)-s-triazine and anadditional 0.16 parts Irgacure 651 were then added to the prepolymerizedsyrup, along with 20.5 parts of Regalrez 6108 tackifier (Hercules Co.).The ingredients were mixed thoroughly until homogeneous and thenknife-coated at a 5 mil thickness onto a silicone-treatedpolyethylene-coated paper release liner. The composite was then exposedto ultraviolet radiation having a spectral output from 300-400 with amaximum at 351 nm in a nitrogen-rich environment. The average intensitywas about 2.05 mW/cm². resulting in a total energy of 650 mJ/cm².

Example 117 was prepared in the same way as example 116 except that themonomer mixture was 77 parts IOA and 23 parts IBA. Also, 13.6 partsRegalrez 6108 was used.

Example 118 was prepared in the same way as example 116 except that themonomer mixture was 71 parts IOA and 21 parts IBA. Also, 7.5 partsRegalrez 6108 was used.

Example 119 was prepared in the same way as example 116 except that themonomer mixture was 84 parts IOA, 15 parts IBA, and 1 part AA. Also,20.5 parts Regalrez 6108 was used.

Example 120 was prepared in the same way as example 116 except that themonomer mixture was 81 parts IOA, 18 parts IBA, and 1 part AA. Also,17.6 parts Regalrez 6108 was used.

Example 121 was prepared in the same way as example 116 except that themonomer mixture was 72 parts IOA, 27 parts IBA, and 1 part AA. Also, 7.5parts Regalrez 6108 was used.

Example 122 was prepared in the same way as example 116 except that themonomer mixture was 83 parts IOA and 17 parts IBA. Also, 5 partsRegalrez 6108 was used.

Example 123 was prepared in the same way as example 122 except that 15parts Regalrez 6108 was used.

Example 124 was prepared in the same way as example 122 except that 30parts Regalrez 6108 was used.

COMPARATIVE EXAMPLE C4

94 parts IOA and 6 parts AA were mixed together in a jar under aconstant nitrogen purge along with 0.04 parts of Irgacure 651photoinitiator from Ciba-Geigy Corp.(2,2-dimethoxy-2-phenylacetophenone). This mixture was partiallypolymerized under a nitrogen-rich atmosphere to provide a coatable syruphaving a viscosity of about 3,000 cps. 0.16 parts of2,4-bis(trichloromethyl)-6-(3,4-dimethoxyphenyl)-s-triazine and anadditional 0.16 parts Irgacure 651 were then added to the prepolymerizedsyrup and it was then knife-coated onto a release coated paper backingat a thickness of 5 mils. The resulting coating was then exposed toultraviolet radiation having a spectral output from 300-400 with amaximum at 351 nm in a nitrogen-rich environment. The average intensitywas about 2.05 mW/cm². resulting in a total energy of 650 mJ/cm².

Comparative example C5 was prepared in the same way as comparativeexample C4 except that a premix of 10 parts AA and 90 parts IOA wasused. In addition, 0.12 parts triazine was used. Comparative example C6was prepared in the same way as comparative example C4 except that apremix of 14 parts AA and 86 parts IOA was used.

Peel and shear data for examples 116-124 and comparative examples C4,C5, and C6 are set forth in Table 4. The data was generated according toTest Procedures A2, B2, and C2.

                                      TABLE 4                                     __________________________________________________________________________    PATENT EXAMPLES FOR TACKIFIED NPAs FOR OILY METAL SURFACES                         Stainless        10 Second                                                                           1 Min.                                                 Steel Peel                                                                         Room Temp   Peel Cold                                                                           Peel Cold                                                                           Percent                                     Example                                                                            24 Hour                                                                            Shear 70° C. Shear                                                                 Rolled Steel                                                                        Rolled Steel                                                                        Conversion                                  __________________________________________________________________________    116  32.6 1020  85    4.0   5.1   >98                                         117  41.9 581   300   4.7   6.7   >98                                         118  40.9 481   331   4.0   4.7   >98                                         119  61.1 1927  426   4.6   10.3  >98                                         120  50.7 5391  338   5.4   9.2   >98                                         121  47.0 10K+  10K+  4.4   8.8   >98                                         122  36.6 127   599   7.3   10.5  >98                                         123  43.5 1314  10K+  9.3   12.4  >98                                         124  56.8 810   17    7.9   12.5  >98                                         C4   51.2 O (DNS)                                                                             O (DNS)                                                                             10K+  nt    >97                                         C5   37.6 O (DNS)                                                                             O (DNS)                                                                             10K+  nt    >97                                         C6   61.5 O (DNS)                                                                             0.7   10K+  nt    >97                                         __________________________________________________________________________

Other embodiments are within the following claims.

What is claimed is:
 1. A tape comprising:(A) a pressure sensitiveadhesive comprising:(a) the reaction product of:(i) 25-98 parts byweight of an acrylic acid ester of a monohydric alcohol whosehomopolymer has a Tg less than (ii) 2-75 parts by weight of a non-polarethylenically unsaturated alkyl acrylate monomer whose homopolymer has asolubility parameter of no greater than 10.50 and a Tg greater than 15°C. selected from the group consisting of 3,3,5 trimethylcyclohexylacrylate, cyclohexyl acrylate, isobornyl acrylate and t-butyl acrylate;and (iii) 0-5 parts by weight of a polar ethylenically unsaturatedmonomer whose homopolymer has a solubility parameter of greater than10.50 and a Tg greater than 15° C.; and (b) at least one tackifier thatis miscible in said polymerization product at room temperature, and (B)a tape substrate.
 2. The tape of claim 1, wherein the tape substrate isa backing having two major surfaces, wherein at least one of thesurfaces is treated with a release coating.
 3. The tape of claim 1comprising:(a) said pressure sensitive adhesive in the form of a firstlayer; and (b) a second layer of an adhesive material.
 4. The tape ofclaim 1 further comprising microspheres.